The present invention relates to digital image processing. More particularly, the present invention relates to a method and apparatus for quickly and efficiently locating a source digital image data file from a large database of source digital image data files based upon a printed input image generated from the desired source image data file. The present invention finds particular application in pixography applications and image reproduction applications such as electrophotographic reproduction apparatus and methods.
The term “pixography” is commonly used to refer to a process involving searching for digital image data for purposes of viewing, distributing, printing or other processing. With the increased popularity of digital photography and digital image processing for photographic and document reproduction applications, a common difficulty encountered by users is the inability to locate the original or source digital image data from which a known printed image has been generated in a large-size digital image database. Digital image databases, whether stored on CD-ROM, magnetic disk drives or other storage media, can be extremely large. For example, one standard CD-ROM can be used to storage data representing at least 1000 high quality JPEG-compressed images. In such case, a user looking for a particular source image data file in the database would be required to actually review each image (or a thumbnail image derived therefrom) until the desired source image could be manually identified. Obviously, for pixography and other consumer oriented applications, this tasks is cumbersome and not likely to be completed. Thus, it is common for the user to scan the printed image as the input image to the pixography or other application, and this leads to image data degradation due to the second-generation reproduction.
Numerous digital image finder methods and apparatus are known. These have been found to be sub-optimal or entirely unsuited for use in applications where cost and complexity must be minimized while speed is maximized. For example, color based system are disclosed in the following documents: (1) G. Ciocca, R. Schettini, L. Conque, Image Indexing and Retrieval using Spatial Chronomatic Histograms and Signatures, CGIV '2002: First European Conference on Color in Graphics, Image and Vision, Apr. 2–5, 2002; (2) G. Ciocca, D. Marini, A. Rizzi, R. Schettini, S. Zuffi, Color Based Image Retrieval of Uncalibrated Images, Proceedings of IEEE on Content-Based Multimedia Indexing, Brescia, pp. 199–206, 2001; and, (3) R. Scheftini, G. Ciocca, S. Zuffi, A Survey of Methods for Colour Image Indexing and Retrieval in Image Databases, Instituto Tecnologie Infomatiche Multimediali (date unknown). Conventional image finder methods such as these and others are necessarily complex for at least the following reasons: (i) the input image to be located in the database is not known to be generated from data in the database; and/or (ii) error is highly undesired in conventional applications.
Based upon the foregoing and similar difficulties, it has been deemed desirable to provide an image finder method and apparatus for pixography and other photo-related reproduction applications that overcomes the foregoing difficulties and others. In particular, it has been deemed desirable to provide a method and apparatus for finding the source data file from which a particular printed image has been generated when the source data file is stored in a large database of source digital image data files.